Metabolic syndrome (MetS), also referred to as insulin resistance syndrome or syndrome X, is characterized by a cluster of conditions, namely: central obesity, dyslipidemia, hypertension and hyperglycemia (Alberti et al., 2005). The detrimental effect of MetS in general is its close association with the development of cardiovascular diseases (CVD) and type 2 diabetes mellitus. A major indicator of the cardiovascular complications associated with MetS is vascular damage which is translated into exaggerated contraction and attenuated dilation of the blood vessels in response to vasoconstrictors and vasodilators respectively (Bahia et al., 2006). Hypertension leading to arterial wall stiffness, as well as atherosclerosis secondary to dyslipidemia, are some of the MetS conditions which catalyze the appearance of the vascular dysfunction observed (Olijhoek et al., 2004; Oliver and Webb, 2003).
Given the detrimental effects MetS has on health, there is a growing interest in the use of natural products, specifically plant polyphenols, combined with synthetic drugs for better control of the disease (Visioli, 2011). Quercetin is a ubiquitous compound, found in many fruits and vegetables including apples, peppers and onions. Quercetin is reported to confer diverse health benefits, such as anti-inflammation, antioxidant and endothelial NO upregulation (Jagtap et al., 2009; Murakami et al., 2008; Shen et al., 2012). Consequently, quercetin is a potential compound that could be used to reduce MetS-initiated vascular damage. However, the exact mechanisms by which quercetin brings forth these advantageous actions remain unclear.
Thus, new formulations are needed for treatment of cardiovascular disorders and to enhance delivery of cardiovascular therapies.